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Search: id:A133944
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| A133944 |
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Sum mu(k), where the sum is over the integers k which are the "non-isolated divisors" of n and mu(k) is the Moebius function (mu(k) = A008683(k)). A positive divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n. |
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+0
2
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| 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, -1, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, -1, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, -1, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, -1, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, -1, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, -1, 0, -1, 0
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A133943(n) = -A133944(n), for n >= 2.
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MAPLE
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A133944 := proc(n) local divs, k, i, a ; divs := convert(numtheory[divisors](n), list) ; a := 0 ; for i from 1 to nops(divs) do k := op(i, divs) ; if k-1 in divs or k+1 in divs then a := a+numtheory[mobius](k) ; fi ; od: RETURN(a) ; end: seq(A133944(n), n=1..120) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 21 2007
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CROSSREFS
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Cf. A133943.
Sequence in context: A025458 A093958 A044936 this_sequence A052434 A094912 A103673
Adjacent sequences: A133941 A133942 A133943 this_sequence A133945 A133946 A133947
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KEYWORD
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sign
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Sep 30 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 21 2007
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